Motorcycles have evolved into specialized forms, as widely different as highway cruisers and dirt bikes. This invention has use particularly on dirt bikes or other motorcycles run off the road in wet conditions, usually while racing.
The standard off road motorcycle includes a front fork assembly that includes a pair of hydraulic shock absorbers, each comprising a hydraulic filled cylinder having a piston assembly working inside the cylinder and a rod extending through the end of the cylinder. One design is to provide the large, or cylinder, end of the shock absorber down with the rod end up. In this design, the cylinder is connected to the wheel assembly and the rod is connected to the steering assembly. A more recent arrangement is to provide the cylinder end up with the rod end connected to the front wheel. This invention relates to motorcycle fork constructions having a hydraulic shock absorber with the cylinder end down.
It has been thought desirable to provide mud guards to prevent mud from accumulating on the rods of the hydraulic shock absorbers. The rods are highly polished to seal against resilient seals in the end of the cylinder. It is easy to see that mud or other abrasive material damages the seals acting between the hydraulic cylinder and rod. Mud guards have been provided for motorcycle forks in which the hydraulic cylinder is up as shown in U.S. Pat. Nos. 4,878,558 and 5,092,421. Another disclosure of interest is found in U.S. Pat. No. 4,138,132.